The present invention relates chiefly to valves for controlling a plurality of fluid circuits simultaneously, of the kind having a body provided with a bore into which open at least one fluid inlet duct and at least one fluid outlet duct forming part of one of said circuits, and a rotary control member housed in the said bore which is adapted to permit or interrupt communication between the said fluid inlet and outlet ducts belonging to one and the same circuit.
Multi-way valves are used, broadly speaking, in any apparatus in which it is necessary to control the flow of a plurality of liquid or gaseous fluids at the same time, whether these fluids are intended to remain seperate or to mix. Amongst other equipment, such valves are fitted to apparatus for operating on materials by flame-produced heat, such as burner torches, which are generally supplied with at least two different gases (such as acetylene and oxygen, propane and oxygen, etc), these gases being conducted through two separate circuits into chambers where they mix and where combustion takes place.
Valves of the above mentioned kind are used in particular to control the two gas circuits of hardening torches. In these known valves, the fluid inlet and outlet ducts of each of the two circuits communicate directly with the above mentioned bore. The control member is formed by a plug having a gentle friction fit in the said bore and which is provided with two orifices which, depending upon the angular position of the said plug, either do or do not allow communication between the inlet and outlet ducts of one and the same circuit.
These known valves have many disadvantages. A changeover from the open position to the closed position can only be achieved by turning the plug, that is to say by an operation which takes up a not inconsiderable period of time, the length of which may be a disadvantage in case of accident, for example when it is necessary for the gas supply to be shut off very quickly. Furthermore, in the closed position the plug does not close off the fluid inlet ducts hermetically and this causes leaks. Finally, such valves do not allow the rates of flow of the fluids to be adjusted gradually nor do they allow there to be a difference in time between the opening (or closing) of one circuit relative to another.